Actuator



Oct. 27, 1964 B. D. ROBERTS 3,153,989

, ACTUATOR Filed April 20, 1961 3 Sheets-Sheet 1 FIG -1 20,

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ACTUATOR Filed April 20, 1961 3 Sheets-Sheet 5 9 FIG -IO FIG 8 n 1 l/\ 1f2? zlo o #221 .qll w 250- -20! 236 246 24; J 349 A Q. 200 I2 l2 I I a240 In: I I I \ZOI O O 22! O O 9 FIG 3/0 30 FIG -II &

INVENTOR.

BRUCE D. ROBERTS ATTORNEYS ,BY 220 256 2 wwwa United States Patent3,153,989 ACTUATOR Bruce D. Roberts, Dayton, Ohio, assignor to CentralStates Tooling Service, Inc., Dayton, Ohio, a corporation of Ohio FiledApr. 20, 1961, Ser. No. 104,435 Claims. (Cl. 92-136) This inventionrelates to actuators and more particularly to a shaft positioning,remote receiver or slave unit of a hydraulic control system.

The apparatus of this invention is particularly adapted for use as adirect throttle actuator for an internal combustion engine, and hasparticular utility for the operation of a fuel metering governor and/ora fuel cut-off valve. An example of one such application of thisinvention is the actuation of the fuel controller of a jet engine in atest cell. Such installations demand that the actuator be reliable, thatit be capable of repeated movement to the same position, as required,that it be easy to assemble or attach to the engine and to remove, thatit hold a given position and not be aifeoted by vibration, and that itbe adapted for rapid and thorough bleeding to remove all air which maybe entrapped therein.

The above requirements and others are fulfilled by the actuator of thisinvention which includes a self-contained piston motor and an outputshaft mounted in a housing which is adapted for quick connection on anddisconnection from a fuel control device, such as the main fuelcontroller on a jet engine. Provision is included for the thoroughpurging of all air which might be entnapped within the cylinder motor sothat when the fluid system is pressurized the piston is eliectivelylocked up for synchronous movement with a remote sending unit. The bodyis preferably divided into a base and an outer housing which arepositionable with respect to each other so that the cylinder motor canbe positioned most advantageously for its operation and for the purgingof entrapped air.

Provision is also preferably included for the internal driving ofotentiometers, remote position transmitters, and the like, so that anoperator may readily ascertain and follow the movement of the throttlecontrol. Also, the unit preferably includes a pair of cylinder motorswith a pair of separate controlled concentric output shafts to providefor the control of two input shafts, such as for the control of fuelflow rate and fuel cut-off.

It is therefore a principal object of this invention to provide a remoteactuator unit characterized by simplicity, ruggedness, versatility, andease of operation.

A further important object of this invention is to provide a remoteactuator unit as outlined above including provision for the thoroughpurging of any air which might be entrapped within hydraulic cylindermotors.

Another object of this invention is to provide an actuator unit asoutlined above characterized by its ease of installation and removalfrom an engine.

A still further object of this invention is to provide an actuator unitas outlined above which is readily adapted for use in existing fuelcontrol systems without modification of the existing sending units orthe compensator units.

Another object of this invention is to provide an actuator unit whichincludes automatic preloading of the engaged gears for the removal ofthe backlash.

A still further object of this invention is the provision of an actuatorunit as outlined above including provision for remote positionindicators.

Another object of this invention is to provide an actuator unit asoutlined above including a pair of separate and isolated hydraulic fluidmotors which are com- 3,153,939 Patented Got. 27, 1954 ice ' shafts andother attachments which create backlash.

A further object is to provide an actuator which may be attached andlocked without safety wiring the attaching bolts.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

In the drawings FIG. 1 is a somewhat diagrammatic elevational view of afuel control system of a jet engine including an actuator unitconstructed according to this invention;

FIG. 2 is -a longitudinal section through the actuator unit of FIG. 1taken generally along the line 22 of FIG. 3;

FIG. 3 is an elevational view of the actuator unit with the cover plateremoved and with one of the hydraulic motors being in section, thissection taken generally along the line 3-3 of FIG. 4;

FIG. 4 is a fragmentary section through a portion of the actuatorshowing the details of the cylinder motors taken generally along theline 4-4 of FIG. 3;

FIG. 5 is a fragmentary elevational detail of a portion of the coverplate and one of the retaining bolts;

FIG. 6 is an enlarged section through a drive gear for a remote positiontransmitter;

FIG. 7 is a perspective view of the backlash preload spring of the gearof FIG. 6;

FIG. 8 is an elevational view looking at the inside surface of theleft-hand cylinder block, with the part being oriented as shown in FIG.4;

FIG. 9 is a section through the left-hand cylinder block taken generallyalong the line 99 of FIG. 8;

FIG. 10 is an elevational view looking into the interior of theright-hand cylinder block with the part being oriented as shown in FIG.4;

FIG. 11 is a section through the right-hand cylinder block showing oneof the bleed valves "and the bleed passageways taken generally along theline 11-11 of FIG. 10; and

FIG. 12 is a further section through the right-hand cylinder blockshowing the bleed valves taken generally along the line 12.12 of FIG.10.

Referring to the drawings, which illustrate a preferred embodiment ofthe invention, a jet engine 20 is somewhat diagrammatically, as it wouldappear on a stand within a jet engine test cell. The jet engine 20includes a fuel controller indicated generally at 22 fixed at the sideof the engine 20. A throttle v alve servo or throttle position actuator25 constructed according to this invention is shown as being mounted onthe controller 22.

The actuator 25 provides the means by which the operation of the jetengine 20 may be remotely controlled by the test cell operatingpersonnel at a remote position within a control room. Thus, the operatormay have before him a fuel control handle 26 and a throttle controlhandle 27 by means of which he controls the operation of the engine 20.The fuel handle 26 is connected to operate the actuator 25 by means of asuitable doubleacting hydraulic fluid displacing device commonly knownas a transmitting or sending unit 38. The unit 30 may consist of anysuitable type of hydraulic transmitting unit, and the part number 13864of Adel Precision Products Corporation, Burbank, California is given asan example of one such unit suitable for this purpose, and forms no partof the present invention. Similarly, the

throttle handle 27 operates another sending unit 31 which may beidentical in construction to the sending unit 51 The unit 39 isconnected to operate the actuator 25 through a pressurized closedhydraulic circuit which includes a pair of hydraulic lines 35 and 36,while the transmitter unit 31 operates the actuator by means of aseparate hydraulic circuit which includes a similar pair of hydraulicleads or lines 37 and 38. Since each of the units 39 and 31 are part ofseparate hydraulic systems, they are preferably separately purged andpressurized by means of suitable compensating units indicated at 41)inserted within the respective hydraulic lines 35-36 and 37-38. Theunits 41) form no part of the present invention, as such, and prefrablyinclude a pump handle 41 and an accumulator portion 42 by means of whichthe hydraulic system involved may be purged of air and pressurized bypumping of hydraulic fluid from a tank or can 45. An example of asuitable compensating unit for this purpose is RN. 15915 of AdelPrecision Products, above.

The actuator 25 preferably includes provision for recording and remoteposition indicating. Thus, a remote position indicator 46 and anoscillograph recorder 47 may be operated by suitable electrical sendingunits lo cated within the actuator, as will be described in greaterdetail hereinafter.

Referring to FIGS. 2-4 and in particular to FIG. 2, the actuator isshown as including a generally cylindrical hollow central body orhousing 511) which supports a cover plate 51 at the outer end thereofand which includes a frame portion or base 52 at the inner end thereof.The cover plate 51 is retm'ned on the housin 50 by screws 53 while thebase 52 is retained on the housing 50 by screws 54. The central housing50 together with the base 52 and cover plate 51 form an assembly whichis suitably secured to the controller 22, shown in broken outlinefragmentary form in FIG. 2, by a plurality of axially extendingretaining bolts 55. The bolts 55 are arranged to extend through thecover plate 51, the interior of the housing 51), and through suitableaxial openings 56 formed within the base 52 and are provided withthreaded inner ends 58 for engagement with suitable tapped holes in thecontroller 22. 'O-rings 59 retain the bolts when the actuator isremoved.

A particular feature of this invention resides in the ease by which theactuator 25 may be connected to and removed from the engine fuelcontroller to save time in the removal of one engine 20 from the teststand and its replacement by another engine. This ease in assembly andin removal is facilitated by the arrangement of the mounting bolts 55including threaded inner ends 58 for the attachment to the controller 22and a head or cap 60 formed on the outer ends and having a transverse orcross pin 61 extending therethrough. The cover plate 51 includes aspider with four radially extending arms 64 mounted on the insidesurface by cap screws 65 and formed with offset portions 66 arrangedadjacent the bolts 55. The portions 66 each support a latch or lockingpin 68 for reciprocal movement.

The pins 68 are formed with a collar 65 thereon and a small compressionspring 71 is interposed between the portion 66 and the collar and serveto bias the pins 68 outwardly through suitable clearance openings formedthrough the cover plate 51. The extended ends of the pins 68 areproportioned to engage the extended ends of the transverse pins 61 toprevent the rotation of the retaining bolts 55 and thus serve to safetythe actuator 25 onto the controller 22.

The pins 68 are readily depressible by a suitable tool such as isindicated at 71 adapted with an opening 72 which may be slipped over theheads 60 in driving engagement with the transverse pins 61 by a slot 73.The tool 71 depresses the pin 68 into an inoperative position whenapplied to the head 61). The tool 71 is proportioned so as to allow thebottom of the slot 73 to travel over the top of the pin 68 withoutinterference. When the tool is removed, the pin 68 returns outwardly toa projecting position in engagement with the transverse pin 61 (FIGS. 2and 5) and thus eliminates the necessity for the use of safety wire.

The base 52 of the actuator includes a mounting flange portion 75adapted for mounting against a suitable flange or cooperating portionformed on the fuel controller with the actuator secured by the bolts 55.The base 52 further includes means for driving the fuel controller inputshafts including a pair of concentric output shafts which are rotatablyreceived within a bearing flange 76 formed in the base 52. Theconcentric shafts includes an outer shaft 80 rotatably mounted on abearing race 81 and formed with a suitable driving connection such asthe tongue 82. An inner shaft 85 has an inner drive end mounted withinthe shaft 89 on a pair of spaced apart bearings 38 and S9, and includesa driven end supported on a bearing received within a bearing supportwall 96 within the center housing 50.

Drive means for the outer shaft 80 includes a main gear 156 secured to aflange 101 on the shaft 80 by bolts 102 and a roll pin 193. The maingear 1110 includes a hub portion 155 rotatably received on a boss 106formed on the inner shaft 85.

Driving means associated with the inner shaft 85 includes a sector gear110 (FIGS. 2 and 3) which is keyed on the inner end thereof and retainedby a nut 112. The gear 110 has the same pitch diameter as the gear 100.

The actuator includes provision for the sending units for remoteposition indicating units, and a precision potentiometer is shown as asending unit for the oscillograph 47 and a position responsive sender116, commonly known as an autosyn, is shown as the sending unit for theindicater 46. These units are mounted on the wall 96 within the housing56 adjacent the extended end of the inner shaft 85 as shown in FIG. 3.Thus, the units 115 and 116 are totally enclosed within the housing 50by the cover plate 51 and are thus protected from dirt.

Means for driving the units according to the position of the outer shaft81) includes the main gear 190 which has mounted thereon a smaller drivegear 12%) joined by a pin to the main gear and held by a snap ring 121.The drive gear 120 comprises the means by which the remote positionsending units are driven in relation to the position of the shaft 81),which is preferably the shaft which operates the throttle mechanism ofthe governor, and thus the units provide an indication of throttleposition. Each of the sending units 115 and 116 are driven off of thegear 121), and the drive arrangement for the autosyn unit is shown inFIG. 2 as having an input shaft 124 and an antibacklash gear 125 indriven relation to the driving gear 120.

The driven anti-backlash gear 125 is formed in two parts as indicated inFIG. 6 and includes an outer relatively thin split portion 126 mountedon a main portion 127 by a spring 136. The main portion 127 is adaptedfor mounting on the shaft 124 and is formed with a pair of diametricallyopposed axially aligned openings 133 and 134 through which the legs 135and 136 of the backlash preload spring may be inserted The legs of thespring are received within suitable clearance openings 138 providedwithin the gear portion 126. The spring 1313 is formed with an arc-likeconnecting portion 141) joining the inner ends of the two legs. The legsand 136 are formed in a slightly non-axial spread apart relation asshown in FIG. 7 wherein the broken lines are parallel to the axis of thegear. When the backlash preloadspring 1511 is assembled within the gear,the legs 135 and 136 preload the split gear portion 126 therebyproviding an unusually compact anti-backlash drive gear for the remoteposition indicators.

The actuator 25 includes separate shaft drive means through which eitheror both of the shafts 85 and 30 may be separately positioned. The shaftdrive means includes a pair of hydraulically separate double-actingcylinder motors, as are best shown in FIGS. 3 and 4. The cylinder motorsare each substantially identical one to the other, and the front motorshown in partial section in FIG. 3 will be described in the greatestdetail, it being understood that the description thereof applies equallyto the more rearward or inner motor, unless otherwise noted. The frontmotor includes means for driving the sector gear 113 and inner shaft 85while the rear motor drives the main gear 1%, the outer shaft 86 and theunits 115 and 116.

The front motor consists of a cylindrical tube 1543 extending throughthe housing 59 transversely of the axis thereof through suitableopenings formed within the housing wall. The cylindrical tube 159 thusforms a hydraulic cylinder which is positioned generally transverse tothe concentric output shafts and contains a double-acting hydraulicpiston member 155 reciprocably received therein. The piston member 155is formed with opposite ends providing bearing surfaces 153 and 159 withthe inside surface of the cylinder 15% and is further provided withsealing means consisting of V-block rings 16th and 161 received withinsuitable recesses formed adjacent the opposite ends of the piston member155. Thus, the portion of the member 155 intermediate the sealing meansis isolated from fluid contact, and is formed of slightly reducedcrosssectional diameter.

Drive means associated with the piston member 155 includes a rack gear163 which extends longitudinally from a position adjacent one of thebearing surfaces 158 to a position adjacent the opposite bearing surface159. The rack gear 163 is preferably formed of hardened steel and ispress-fitted into engagement with a cooperating slot formed within themember 155, which may be formed of aluminum.

The cylinder 150 has one side thereof cut away as indicated at 165 toform an opening centrally thereof positioned inwardly toward theinterior of the housing 56). This opening 165 provides clearance for themovement of the sector gear 114 therein in engagement with the rack 163.Also, the piston member 155 has a portion thereof cut away adjacenteither side of the rack 163 as indicated at 166 and 167 for the purposeof facilitating assembly.

The bearing surfaces 158 and 159 are provided with a running clearancewithin the cylinder 150 in the order of a few thousandths of an inch.This running clearance provides a small amount of freedom of movement ina direction transverse to the axis of the cylinder. The pressurizationof the hydraulic system effects the expansion of the V-block rings 16%and 161. Therefore, when the rings 16% and 161 are pressurized, thepiston member 155 tends to be held centrally of the cylinder 15% andurges the engagement of the rack 163 with the teeth of the gear 11d.Thus, this arrangement provides, in effect, for the fluid cushionedengagement of the associated rack and gear with a minimum of backlash orclearance. Pressure relief openings 179 between the V-ring recesses andthe outside surface of the heads provide for pressure relief upon thereversal of movement of the member 153 and further provide for thecomplete relief of pressure within the rings upon disassembly of theactuator.

The hydraulic fluid motor mechanism for driving the main gear 160 isessentially the same as that which has so far been described inconnection with the sector gear 110, and the parts thereof including thecylinder 150 and the piston member 155 of each of these motors are, infact, preferably interchangeable. One difference exists, however in theprovision of a spacer 172 having a fluid access opening 173 therethroughand positioned within the cylinder 150 of the front motor to preventexcess travel of the member 155 in relation to the gear 11%. It is, ofcourse, within the scope of this invention to provide a full 360 gear inlieu of the sector gear 110, and relatively longer or shorter rack gears163. It is further within the scope of this invention to provide anydegree of angular rotation of the shafts and according to therequirements of the governor or other controlling device which may bepositioned by this actuator.

The opposite open ends of each of the cylinders are enclosed withincylinder blocks and are held in the assembled position by tie bolts. Thecylinder blocks provide the means by which fluid pressure may beadministered selectively to either side of each of the fluid motors andfurther provide the means by which each of these motors may be bled andpurged of air upon assembly. The block 206) on the left-hand side willbe described first and reference may therefore be had to FIGS. 4, 8 and9 for a detailed showing thereof. The cylinder block 200 is formed withbored openings 201 within which the extended ends of the cylinders 150are received. An O-ring 262 provides a fluid seal between the block 2%and the outside surface of each of the cylinders 15% The block 2% istapped from the outside surface inwardly at 205 and 206 to provide forthreaded inlet connectors 20S and 209. These tapped openings 205 and 2%extend into the interiors of the respective cylinders 150 throughannular spacer disks 21d and provide the means by which hydraulic fluidmay be administered to the left side of each of the motors.

Means for retaining the block 2% in its assembled position over the endsof the cylinders 150 include four elongated bolts 215 which pass throughsuitable clearance openings formed adjacent the four corners of theblock 2%. The bolts 215 have threaded inner ends which are receivedwithin tapped openings formed through the wall of the housing 50, asshown in FIGS. 3 and 4.

The right-hand cylinder block 225 is formed with a pair of inwardlyfacing openings 221 similar in function and purpose to the openings 2111of the block 2% to receive the extended ends of the cylinders 150therein. O-rings 222 provide a seal therewith. The block 220 is retainedin a manner similar to that described above and includes a retainer cap225 mounted on the outer surface thereof, the purpose and function ofwhich will be described below. The assembled retainer cap 225 and theblock 220 are secured by four longitudinally extending bolts 226 passingthrough the body and cap and threaded into the housing 54 Means foradmitting fluid into the interior of the cylinder 150 at the right-handend of the piston members includes a pair of tapped openings 228 and 229(FIG. 4) formed at right angles to the pistons. The openings 228 and 229connect with drilled passageways 230 (FIGS. 3 and 10) joining the tappedopenings and the interior of the cylinders 15%.

An important feature of this invention resides in the provision of meansfor purging each of the hydraulic cylinder motors of all entrapped airtherein. This is particularly important to the successful operation ofan actuator in a jet engine test stand wherein its is desired that theactuator be readily assembled and brought into a state of operation witha minimum of time and delay. It is also essential to proper operationthat all air be removed so that the piston members 155 accurately followand reproduce the position of the handles 26 and 27 of the sendingunits.

In general, the bleeding of the hydraulic motor portion of the actuatorsis accomplished, in part, by externally positioned bleed passageways ortubes, one being provided for each of the hydraulic motors. The bleedingoperation is effected by providing for the circulation of hydraulicfluid into one of the inlets at one of the blocks, through the externalbleed passageway and out of the inlet at the opposite block. Thiscirculation is effected by the pump of the compensator.

In particular, the bleed system includes means connecting the respectivefluid chambers of each of the hydraulic motors at each of the cylinderblocks in the form of a pair of tubes 240 and 241 which extend betweenthe cylinders through suitable openings provided within the wall of thecentral housing 50. The tubes 240 and 241 are shown in section in FIG. 2between the cylinders 15% and the end connections thereof are shown inFIGS. 812.

Referring to FIGS. 8 and 9, it is seen that an annular groove or recess245 is formed at the end Wall defining the opening 2521 behind the disk21d and a diagonal drilled passageway 246 connects the annular groove245 to an axial passageway 248 which, in turn, is formed with a recessedportion 24s to receive the innermost end of the bleed tube 240. As shownin FIG. 8, similar passageways are provided in the left cylinder blockfor the other hydraulic motor. Also as shown in FIG. 8, each of thedisks 210 include a bleed opening 25513 which, upon assembly, ispositioned upwardly in accordance with the operating position of theactuator so that it is at the high point of the associated fluidchamber.

As shown in FIGS. -12, the opposite extended ends of the bleed tubes 240and 241 are supported within suitable openings formed within the rightcylinder block 220, and are connected to their respective fluid chamberswithin the cylinders 155 through bleed needle valves 255 and 256 whichare threaded into suitable valve openings formed within the cylinderblock 220. There is provided one bleed valve for each of the tubes 24dand 241. The bleed valves are normally closed with their pointed ends257 threaded against the inside ends 258 of their respective tubes. Thecap 225 serves as a retainer for the valves 255 and 256 and is formedwith access openings 260 through which the needle valves may be eitheropened or closed. A passageway 262 connects each of the valves to arelieved portion 263 formed within the cylinder block 220 at the base ofthe openings 221 thereby connecting the tubes 244) and 241 to theirrespective hydraulic chambers for air purging.

In the purging operation, the associated handle 4-1 of one of thecompensators 40 is operated to draw hydraulic fluid from the tank 45 andto apply this fluid under pressure to one of the inlet connectors 208 or209 through the hydraulic lines. It is preferable that the hydraulicfluid be applied to the inlets at the cylinder block 200 for circulationthrough their respective hydraulic chambers within the cylinders 159through the tubes 24% and 241, and through the chambers in theright-hand cylinder block 222. The bleed valve 255 or 256 associatedwith the particular motor being purged is opened to provide flow of thehydraulic fluid externally of the hydraulic motors from the fluidchamber in the block 2% to the opposite chamber within the block 22%.The disk 21% is preferably positioned on assembly to place the bleedopening 250 upwardly with respect to the block 206) to provide for theremoval of all air which may have been entrapped therein.

In this manner, by observing the condition of the hydraulic fluid beingreturned to the tank 45 for the absence of all air bubbles, each of thehydraulic motors may be quickly and thoroughly purged of all entrappedair. The associated bleed valve 255 or 256 is then closed and the handle41 is further operated to pressurize the system by means of theaccumulator portion 42 of the compensator 4h. The system may bepressurized in the order of 650 p.s.i., as an example. The system is nowready for operation by the fluid pressure transmitting units 30 and 31.

The hydraulic cylinders are preferably mounted in the horizontalposition for the most advantageous purging of air. However, it may bedesirable to mount the cylinders in another position due to the spacerequirements. Therefore, the actuator includes provision for themounting of the housing 51) in any one of four 90 positions with respectto the base 52. This is readily accomplished by the removal of the bolts55 and the removal of the machine screws 54. The housing 50 may then beturned relative to the base 52 into a new quadrature position and thescrews 54 re-inserted.

In the operation of the actuator subsequent to purging and pressurizingdescribed above, movement of one of the handles 26 or 27 effectstransverse positioning of one of the piston members 155. This, in turn,is directly translated to the rotation of one of the gears I06 orthrough the rack I63 carried by the piston member. There is a minimum ofbacklash in this mechanism due to the effect of the pressurization ofthe V-block rings 160, 161 which urge the piston member 155 centrallywithin the cylinder and urge the engagement of the rack and gear.

The transmitter units and 116 are similarly positioned in accordancewith the position of the main gear Elli through the anti-backlash gears125. Thus, the position of the outer shaft fill may be constantly readat the indicator 46 and recorded at the oscillograph 47. The inner shaft85 may be most conveniently employed as the fuel shut-otf control.

Although the embodiment herein shown and described includes concentricshafts and dual hydraulic motors, it is understood that it is within thescope of this invention to provide a single useful shaft operated by asingle hydraulic motor arranged according to this invention. Further,the tie bolts which secure the cylinder blocks may be extended entirelythrough the housing. Also, the pins 68 may be received within suitablycountersunk openings formed in the housing wall rather than beingsupported by the spider 64.

It is therefore seen that this invention provides a compact receiver oractuator. It is to be understood that the use of this invention is notlimited to application to governors on jet engines, as illustrated anddescribed, but may be used with advantage in any installation whereexact positioning of one or more shafts, levers or the like is required.Thus, the invention may be used with advantage for the remote control ofpower settings for diesel engines and the like which may, for instance,be controlled remotely from a flying bridge on a boat.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. A throttle valve control servo comprising a housing, a onepiececylindrical tube supported in and extending through said housing, adouble-acting piston member received in said tube and having oppositepiston ends in spaced relation to the ends of said tube and forming afluid seal with the inside wall surface of said tube, the movement ofsaid piston member in said tube being wholly confined to the axiallimits of said tube, means in said tube defining an opening centrallythereof and positioned inwardly to said housing, a rack gear formed insaid piston member adjacent said opening, an output shaft rotatablymounted in said housing and having a gear thereon in intermeshingrelation with said rack gear for rotational movement in said openingupon the transverse movement of said piston member, a separate cylinderhead block carried on each end of said tube closing the ends thereof andforming fluid chambers Within said tube adjacent said piston ends, tiebolt means extending through each said cylinder head block and extendinginto said housing retaining said head blocks in closing relation to theends of said tube and retaining sadi tube in fixed axial position inrelation to said housing, and flud inlet means in each of said blocksconnected to said cham ber providing passageways for the application ofhydraulic pressure to said chambers to effect transverse positioningmovement of said piston member in said tube.

2. A throttle valve control servo comprising a generally cylindricalhousing, a one-piew cylindrical tube extending transversely of saidhousing on an axis radially spaced from the axis of said housing andhaving a central portion thereof received in said housing with theopposite ends thereof extending outwardly of said housing, adouble-acting piston member received in said tube and having oppositepiston ends in spaced relation to the ends thereof, means in said endsforming a fluid seal with the in side Wall surface of said tube, meansin said tube defining an opening intermediate the ends thereof andopening into said housing, a rack gear formed in said piston memberadjacent said opening, an output shaft rotatably mounted in said housingand having a gear thereon in intermeshing relation with said rack gearfor rotational movement in said opening upon the transverse movement ofsaid piston member, a separate cylinder block carried on each end ofsaid cylinder tube closing the ends thereof and forming fluid chambersWithin said tube adjacent said piston ends, tie bolts extending througheach said cylinder blocks and into said housing for locating saidcylinder tube in said housing and removably securing said blocks on saidends thereof, and fluid inlet means in each of said blocks providingpassageways for the application of hydraulic pressure to said chambersto efifect transverse positioning movement to said piston member in saidtube.

3. A remotely controlled throttle position actuator for ready attachmentand removal from jet engines in an engine test stand, comprising ahousing, coupling means in said housing adapted for connection to theinput shaft of a throttle controller on said jet engine, a slavedhydraulic piston motor in said housing, means connecting said pistonmotor to said coupling means to position said controller shafttherethrough, means removably connecting said housing to said controllerincluding a plurality of bolts extending through said housing havinginner ends adapted for removable connection to said controller andexposed outer ends adapted for the application of a driving toolthereto, a cross pin extending through each of said outer ends, a latchpin for each of said bolts mounted in said housing adjacent theassociated said bolt, the outer end of said latch pin being proportionedfor engagement with one of said cross pins to prevent rotation of theassociated said bolt, and means mounting said latch pin providing formovement thereof by the application of a driving tool to said outer endinto a retracted position clear of said cross pin, and bias means urgingsaid latch pin outwardly into an outer position in interferingengagement With said cross pin.

4. A remotely controlled actuator for attachment to and removal from amechanism having a shaft to be controlled thereby, comprising a housing,coupling means adapted for connection to such shaft to be positioned bysaid actuator, a hydraulic piston motor in said housing, meansconnecting said piston motor to said coupling means to position suchshaft therethrough, means removably connecting said housing to saidmechanism including at least one threaded fastener extending throughsaid housing having an inner end adapted for removable connection tosaid mechanism and an exposed outer end adapted for the application of adriving tool thereto, means forming a cross pin extending transverselyof said fastener at said outer end, a latch pin mounted on said housingadjacent said fastener outer end, said latch pin being proportioned forinterfering engagement With said cross pin to prevent rotation of thesaid fastener, said means mounting said latch pin providing for movementthereof by the application of a driving tool to said fastener outer endinto a retracted position clear of said cross pin, and bias meansnormally urging said latch pin into said interfering engagement withsaid cross pin means.

5. A remotely controllable dual servo actuator comprising a housing, apair of one-piece cylindrical tubes extending transversely of saidhousing and each having a central portion extending through a portion ofsaid housing with the ends of said tubes extending outwardly of saidhousing, said tubes being positioned in relatively axial spaced relationwith respect to said housing, a separate piston member received in eachof said tubes for application of hydarulic fluid to the opposite endsthereof and having means in each of said ends forming a fluid seal withthe inside Wall surface of the associated said tube, means in each ofsaid tubes defining an opening intermediate the ends thereof and facinginto said housing, means forming a rack gear on each of said pistonmembers accessible through said tube openings, a pair of shaftsrotatably mounted in said housing and each having a gear thereonreceived in intermeshing relation with one of said rack gears foreffecting rotational movement of one of said shafts With the positioningmovement of one of said piston members, a pair of cylinder head blockshaving means forming tube-receiving openings therein with one each ofsaid blocks received over the adjacent extended ends of said tubesforming a common cylinder head for said tube pairs at each of theextended ends thereof, said cylinder head blocks each having separatefluid inlet means in communication With the ends of each of said tubesfor application of hydraulic fluid to the associated said piston member,and tie bolts extending through each of said blocks and into saidhousing retaining said blocks in closing relation to said pairs of tubeends and locating said tubes in fixed position in relation to saidhousing.

References Cited in the file of this patent UNITED STATES PATENTS1,464,612 Madler Aug. 14, 1923 2,079,684 Church May 11, 1937 2,207,635Nardone July 9, 1940 2,262,432 Rodder et val Nov. 11, 1941 2,286,661Warner June 16, 1942 2,465,358 Curtis et al Mar. 29, 1949 2,509,991Schenke May 30, 1950 2,782,602 Hamilton Feb. 26, 1957 2,880,580 Wallaceet a1 Apr. 7, 1959 2,997,756 Stone Apr. 4, 1961 FOREIGN PATENTS 426,069Italy Oct. 21, 1947 1,204,374 France Aug. 10, 1959 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No, 3 153389 October 27 1964Bruce D. Roberts It is hereby certified that error appears in the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below.

Column 1, line 45 for "separate" read separately column 3, line 14 for"prefrably" read perferably column 6, lines 43 and 44L for "cylinder"read cylinders column 8, line o l for "sadi" read said line 65 for":Elud" read fluid column 9 line 2O for "to" read of column 10, line l7for "hydarulic" read hydraulic line 53 for "2,997 756" read 237L756Signed and sealed this 30th day of March 1965 (SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER AttcstingOfficer

1. A THROTTLE VALVE CONTROL SERVO COMPRISING A HOUSING, A ONE-PIECECYLINDRICAL TUBE SUPPORTED IN AND EXTENDING THROUGH SAID HOUSING, ADOUBLE-ACTING PISTON MEMBER RECEIVED IN SAID TUBE AND HAVING OPPOSITEPISTON ENDS IN SPACED RELATION TO THE ENDS OF SAID TUBE AND FORMING AFLUID SEAL WITH THE INSIDE WALL SURFACE OF SAID TUBE, THE MOVEMENT OFSAID PISTON MEMBER IN SAID TUBE BEING WHOLLY CONFINED TO THE AXIALLIMITS OF SAID TUBE, MEANS IN SAID TUBE DEFINING AN OPENING CENTRALLYTHEREOF AND POSITIONED INWARDLY TO SAID HOUSING, A RACK GEAR FORMED INSAID PISTON MEMBER ADJACENT SAID OPENING, AN OUTPUT SHAFT ROTATABLYMOUNTED IN SAID HOUSING AND HAVING A GEAR THEREON IN INTERMESHINGRELATION WITH SAID RACK GEAR FOR ROTATIONAL MOVEMENT IN SAID OPENINGUPON THE TRASVERSE MOVEMENT OF SAID PISTON MEMBER, A SEPARATE CYLINDERHEAD BLOCK CARRIED ON EACH END OF SAID TUBE CLOSING THE ENDS THEREOF ANDFORMING FLUID CHAMBERS WITHIN SAID TUBE ADJACENT SAID PISTON ENDS, TIEBOLT MEANS EXTENDING THROUGH EACH SAID CYLINDER HEAD BLOCK AND EXTENDINGINTO SAID HOUSING RETAINING SAID HEAD BLOCKS IN CLOSING RELATION TO THEENDS OF SAID TUBE AND RETAINING SAID TUBE IN FIXED AXIAL POSITION INRELATION TO SAID HOUSING, AND FLUID INLET MEANS IN EACH OF SAID BLOCKSCONNECTED TO SAID CHAMBER PROVIDING PASSAGEWAYS FOR THE APPLICATION OFHYDRAULIC PRESSURE TO SAID CHAMBERS TO EFFECT TRANSVERSE POSITIONINGMOVEMENT OF SAID PISTON MEMBER IN SAID TUBE.